Two way CATV systems are well known. Techniques for utilizing the bidirectional nature of such networks for digital data transmission have been developed. For example see U.S. Pat. No. 3,803,491 to Osborn and U.S. Pat. No. 4,245,245 to Matsumato et al. A wide variety of consumer services such as home banking, electronic mail and newspapers, shop at home, and the like, are envisioned to become commonplace.
However, the systems developed to date have failed to achieve widespread use. One of the reasons for the lack of general acceptance is that prior art systems centralize digital communication at the headend of the CATV system. That is digital messages are exchanged between the headend and the user nodes. Such concentration of network intelligence at the headend node has several disadvantages.
Firstly, a centralized network design requires that many participants, particularly the cable operator, the service provider, and the equipment manufacturer, undertake coordinated activities simultaneously to assure that equipment and data formats are compatible. The reluctance of each individual party to act until a settled system architecture emerges has been an important factor in the delayed development of two way CATV data services. Also, a centralized network architecture results in complex and cumbersome headend equipment. The headend software in such prior art systems is typically multi-tasking in order to process different data services simultaneously. Therefore, adding new services to existing services can be difficult. Furthermore, as entirely new services are added to the system, the capability of a centralized system may be exceeded, requiring that the entire headend architecture be redesigned to accommodate all of the desired services.
Furthermore, system reliability is compromised when system intelligence is centralized: A single failure at the headend can disable all of the two way CATV services.
Finally, in a centralized system, the cable system operator is closely involved with the service providers and is burdened with such problems as information privacy, data integrity and disputes over rights of access to consumers by competing service providers.